Automatic cam trip



May 18, 1954 A. s. CASWELL AUTOMATIC CAM TRIP 3 Sheets-Sheet 1 Filed Sept. 19, 1950 INVENTOR. 71776 14? .5. 43m? In AWE y 18, 1954 A. s. CASWELL 2,678,976

AUTOMATIC CAM TRIP Filed Sept. 19, 1950 3 Sheets-Sheet 2 Wviil May 18, 1954 Filed Sept. 19, 1950 A. S. CASWELL AUTOMATIC CAM TRIP 3 Sheets-Sheet 3 INVENTOR.

BY VLM Patented May 18, 1954 AUTOMATIC CAM TRIP Arthur S. Caswell, Philadelphia, Pa., assignor to I-T-E Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Application September 19, 1950, Serial No. 185,573

9 Claims. 1

My present invention relates to draw-out type circuit breakers of the type adapted to be inserted into and withdrawn from a compartment and movable between an operative and a test position; and more particularly to an automatic tripping device adapted to trip the circuit breaker automatically on the initiation of the draw-out movement of the circuit breaker so that interruption of or the establishment of a current path and extinguishment of the arc will take place at the circuit breaker contacts which are designed for this operation and not at the disconnects which are designed only to carry current and not to interrupt current.

My invention contemplates an improvement of the circuit breakers disclosed in Patent Nos. 2,611,838, issued September 23, 1952, and 2,613,299, issued October '7, 1952, wherein the racking bar is provided with an extension carrying a cam roller; the circuit breaker housing is provided with a. slotted cam cooperating with the roller.

; The racking bar mounted on the circuit breaker is stationary with respect to the, enclosure compartment during the racking-in or -out of the circuit breaker; that is, the racking bar is usually connected to a screw so that the screw may rotate with respect thereto While it has longitudinal movement with respect to the racking bar.

*Thus, when the racking bar is securely anchored in the compartment, rotation of the screw byan appropriate tool or handle will cause the circuit breaker to move in or out with respect to the enclosure compartment.

The cam is arranged so that when depressed in a. counter-clockwise direction it will rotatively operate the tripper bar of the circuit breaker to trip the circuit breaker open. The cam has a slot engaged by the cam roller, the slot being so designed that the cam will be depressed in all horizontal positions of the circuit breaker between the fully racked-in and fully racked-out positions.

Therefore, on initiation of a racking out operation, if the circuit breaker has not already been tripped open, it will automatically be tripped open before the disconnect contacts have disengaged and will be locked in tripped position until the fully racked out or test position is reached.

Heretofore the cam was mounted on the eubicle to engage the latch shaft extension mounted on the circuit breaker. Any variation in dimension in the circuit breaker or the cubicle resulted in misoperation. In addition the circuit breakers in switchgear are required to be interchangeable. Any circuit breaker must enter all cubicles of any installations and the interlocking must work. It is much easier to maintain this operation when the cam and the latch extension are an integral part of the circuit breaker and adjusted to that breaker. Variation in dimension of the cubicle no longer affects the operation. Interchangeability is easier to secure and more positive and safe. Accordingly an object of my invention is to provide a mechanical interlock integral with each individual drawout circuit breaker so that interchangeability of each circuit breaker within all similar circuit breaker compartments will not be operatively affected by slight variations in individual adjustments of aforementioned interlock device.

A further object of my invention, therefore, is the provision of novel automatic tripping means for a circuit breaker operable on the initiation of the racking-in or the racking-out operation.

Another object of my invention is the provision of automatic trip means for a draw-out circuit breaker which will maintain the circuit breaker in trip position during the racking out operation so that the circuit breaker cannot be closed at any position other than the fully racked-in or Operative position or the fully racked-out of Test position.

Another object of my invention is the provision of a cam roller on the racking bar and cam on the drawout circuit breaker, the cam being operable by the roller to trip the circuit breaker automatically on the initiation of either of the racking movements.

The foregoing and many other objects of my invention will become apparent in the following description and drawings in which:

Figure 1 is a schematic view in perspective of the racking bar, roller, cam and trip unit of my invention.

Figures 2, 3, and 4 are successive side views of the cam, roller and trip bar showing, respectively, the fully racked in, the partially withdrawn and the fully racked out positions of the circuit breaker.

Figure 5 is a view in perspective of the circuit breaker showing the automatic trip unit mounted thereon.

Figure 6 is a side view partly in cross-section of the draw-out circuit breaker in the compartment in a partially racked out position intermediate the Operative and Test positions.

The circuit breaker I00 of Figures 5 and 6 is the circuit breaker described and shown in Patent No. 2,611,838, issued September 23, 1952, which, however, is used by way of example only 3 since my invention is applicable to other drawout circuit breakers having trip mechanism which can be operated to trip position by rotational movement.

The racking bar 406 of Figures 1, 5, and 6 corresponds to the racking bar 405] of Figures 1, 10, 11 and 12 of the said patent; its operation requires no specific description here (and the description with respect to said figures is incorporated herein by reference).

It is sufficient to point out that racking bar tee has a screw Hi mounted in opening ii thereof in such manner that it may rotate with respect thereto while having longitudinal movement with respect thereto. The screw iii is in rotatively free engagement with bearing it in the circuit breaker.

Consequently, when the circuit breaker is wheeled into the compartment tilt (Figures and 6) and the racking bar 468 is engaged with c the compartment 2&9 to be relatively stationary with respect thereto, rotation of end 15 of screw Iii (Figure l) in housing it (Figures 5 and 6) will cause the circuit breaker to move in from the Test position to the Operative position and vice versa.

The circuit breaker has the trip mechanism 2% and contact structure 21 described in the said PatentNo. 2,611,838 issued September 23,

1952, the essential element of which for ap- :2.

plication is the latch bar 26 pivotal on shaft 26 and having a latch end 21 engaging trip shaft 23 adjacent the milled portion 29 thereof.

When shaft 28 is rotated clockwise with respect to Figure l, latch end 2": of latch bar will enter milled portion 29 of trip shaft 28 and the circuit breaker will trip open. if shaft 28 is held in this rotated position, the circuit breaker will remain tripped until the shaft 23 is preniitted to return counterclockwise to its original. position. Consequently, the circuit breaker, since it is trip-free, cannot be closed while shaft 23 is in the clockwise rotated posttion.

For purposes of the present invention, shaft 23 is extended at 28a to one side oi the circuit breaker where it is provided with crank arm 39 keyed thereto. The crankarm 3&3 maybe an extension of the well-known tripper bar which is operated 'by electromagnetic means to trip the circuit breaker.

The side 'wall id 'of the circuit breaker housing carries the cam 58 rotatably mounted on pin 5l carried by the-side wall 48 or the frameof the oircuitbrea-ker.

The racking bar 4233 has an adjustable stud E5 mounted therein which carries the vertically adjustable screw 'fiwhich in turn carries the cam roller bar 51 normal to the racking bar. This "form of mounting of the cam roller bar 5? permits adjustment thereof to locate the roller 60 relatively with the cam-50. Cam roller bar 57 has a bracket 61 which carries cam roller 60. Cam roller 60 rides in the cam slot 65 in cam 5d.

Bracket 56 on side wall it is provided with parallel flanges 6i, Bit-having the aligned openings 69 and 76 in order to furnish a support for the cam roller bar 51 and thereby maintain the cam roller 6!! in a rigid horizontal position.

The cam slot 65 as is seen more particularly in Figures 2, 3 and 4 comprises a substantially horizontal section 65a, a downwardly curved section 65?) at the outer end and a downwardly curved section 65c at the inner end adjacent the pivot 5|.

The downwardly curved section 550 is so posi tioned that when the circuit breaker is fully racked-out, the roller (it) will register with section 650 of slot 65 and raise the end a of cam W to a substantially horizontal or slightly raised position.

Likewise, the downwardly curved section 8512 at the outer end is so arranged that when the circuit breaker is fully racked in, the cam roller 66 Will register therewith and also raise the cam to a substantially horizontal or slightly raised position with portion 5E2 of the cam 55 raised.

When, however, the circuit breaker is positioned interniediately between the Operative and the Test positions and the roller is set at the horizontal section 55a of the slot 55, then the end We of the cam at will be depressed. Owing to the curvature of sections 652) and 650 of the slot with respect to section a of the slot 65, the roller Bil will register with the horizontal section 65a of slot 65 during virtually all of the travel of the circuit breaker between :the racked-out or Test position and the rackedin Or Operative position.

Also, immediately upon movement of the circuit breaker from the racked-in position and before the primary disconnect contacts "l0ll (Figure 6) have disengaged, the cam will be moved so that the roller '60 registers with section 65a of the slot and thecam is depressed to rotate the crank-arm 31', to trip the circuit breaker.

is should here again be noted that the racking bar tilt is relatively stationary with respect to the compartment 2% andthat,'therei'ore, the roller 8! is relatively stationary Withiespect-to the compartment Zilil since it is supported solely from racking bar 438.

The remainder of the circuit breaker moves with respect to the compartment 238 on rotation of the screw it! by a handle or other operating means associated with the end id of the screw It as above described.

The end 58a of the cam 50 registers with and bears upon the pin ti. connected to thecrank arm 33 and is so arranged that whenthe cam 59 is raised the crank arm 36 and the mill'ed shaft Zilare in the non-trip position of the cir cuit breaker mechanism but when the cam- 50 is lowered byth'e engagement of roller EU in slot sections 65a, the end 50a of the cam will press down the roller-B8 on crankarmBO-bfthe trip shaft 28 andmove the trip shaft 28 to the trip position.

Consequently, immediately upon initiation of the racking-out operation, the circuit breaker will automatically be moved to the trip position of the cam 5c and will remainin .the trip position until the racking out operation is completed, at which time'the roller moves into registry with slot sectionliiib permitting the cam to be raised once more and permitting the milled shaft"218 to move back to non-trip position.

Thus, the circuit breaker can be operated only in the fully-racked-out or fully racked-inpasition and is automatically tripped at any position therebetween and, therefore, will-automatically be tripped upon any attempt 'to rack out the circuit breaker at a time when'thecircuit breaker is closed.

In theforegoing vI have describedmy invention solely in connection with specific illustra tive embodiments thereof. sincezmany variations and modifications of my invention will'now 'be obvious to those skilled in the art, I preierto lbe bound not by the specific disclosures herein contained but only by the appended claims.

I claim:

1. A circuit breaker constructed for movement into and out of a cubicle and having primary disconnect contacts, said circuit breaker having a circuit closed and a trip open position, a trip mechanism for operating said circuit breaker to its trip open position, a screw carried by said circuit breaker, a racking bar carried by said screw, a locking member mounted on said cubicle for securing said racking bar to said cubicle to permit movement of said screw and circuit breaker relative to said racking bar and cubicle for racking said circuit breaker into racked-in and racked-out positions; a cam mounted on said circuit breaker, a cam follower mounted on said racking bar engaging said cam, a cam follower .bar connection from said cam follower to said trip mechanism, said cam having a surface at one end thereof engageable by said follower when said circuit breaker is in its racked-in position and having a surface engageable by said follower at its other end when said circuit breaker is in its racked-out position and having a surface intermediate said position engageable by said follower so that said cam follower is instantly operated by the racking out of said cam when said circuit breaker starts for operating said circuit breaker to its trip open position before said disconnects disengage and for positively maintaining said circuit breaker in its trip open position until said circuit breaker has been moved to its racked-out position.

2. A circuit breaker constructed for movement into and out of a cubicle and having primary 1 disconnect contacts, said circuit breaker having a circuit closed and a trip open position, a trip mechanism for operating said circuit breaker to its trip open position, a screw carried by said circuit breaker, a racking bar carried by said screw, a locking member for securing said racking bar to said cubicle to permit movement of said screw and circuit breaker relative to said racking bar and cubicle for racking said circuit breaker into racked-in and racked out positions; a cam mounted on said circuit breaker, a cam 'follower mounted on said racking bar engaging said cam, a cam follower bar connection mounted on said racking bar and providing a connection from said cam follower to said trip mechanism, said cam having a surface at one end thereof engageable by said follower when said circuit breaker is in its racked-in position and having a surface engageable by said follower at its other end when said circuit breaker is in its racked-out position and having a surface intermediate said position engageable by said follower so that said cam follower is instantly operated by said cam when the racking out of said circuit breaker starts for operating said circuit breaker to its trip open position before said disconnects disengage and for positively maintaining said circuit breaker in its trip open position until said circuit breaker has been moved to its racked-out position.

3. A circuit breaker constructed for movement into and out of a cubicle and having primary disconnect contacts, said circuit breaker having a circuit closed and a trip open position, a trip mechanism for operating said circuit breaker to its trip open position, a screw carried by said circuit breaker, a racking bar carried by said screw, a locking member for securing said racking bar to said cubicle to permit movement of said screw and circuit breaker relative to said racking bar and cubicle for racking said circuit breaker into racked-in and racked-out positions; a cam mounted on said circuit breaker, a cam follower mounted on said racking bar engaging said cam, a cam follower bar connection mounted on said racking bar and providing a connection from said cam follower to said trip mechanism, said cam having a surface at one end thereof engageable by said follower when said circuit breaker is in its racked-in position and having a surface engageable by said follower at its other end when said circuit breaker is in its racked-out position and having a surface intermediate said position engageable by said follower so that said cam follower is instantly operated by said cam when the racking out of said circuit breaker starts for operating said circuit breaker to its trip open position before said disconnects disengage and for positively maintaining said circuit breaker to its trip open position until said circuit breaker has been moved to its racked-out position, and an adjusting mechanism mounted on said circuit breaker for adjusting said connection to properly position said cam follower on said cam.

4. A circuit breaker constructed for movement into and out of a cubicle and having primary disconnect contacts, said circuit breaker having a circuit closed and a trip open position, a trip mechanism for operating said circuit breaker to its trip open position, a screw carried by said circuit breaker, a racking bar carried by said screw, a locking member for securing said racking bar to said cubicle to permit movement of said screw and circuit breaker relative to said racking bar and cubicle for racking said circuit breaker into racked-in and racked out positions; a cam mounted on said circuit breaker, a cam follower mounted on said racking bar engaging said cam, a cam follower bar connection mounted on said racking bar and providing a connection from said cam follower to said trip mechanism, said cam having a surface at one end thereof engageable by said follower when said circuit breaker is in its racked-in position and having a surface engageable by said follower at its other end when said circuit breaker is in its racked-out position and having a surface intermediate said position engageable by said follower so that said cam follower is instantly operated by said cam when the racking out of said circuit breaker starts for operating said circuit breaker to its trip open position before said disconnects disengage and for positively maintaining said circuit breaker in its trip open position until said circuit breaker has been moved to its racked-out position, and an adjusting mechanism mounted on said racking bar for adjusting said connection to properly position said cam follower on said cam.

5. A circuit breaker constructed for movement into and out of a cubicleand having primary disconnect contacts, said circuit breaker having a circuit closed and a trip open position, a trip mechanism for operating said circuit breaker to its trip open position, a screw carried by said circuit breaker, a racking bar carried by said screw, a locking member for securing said racking bar to said cubicle to permit movement of said screw and circuit breaker relative to said racking bar and cubicle for racking said circuit breaker into rackedin and racked-out positions, a circuit breaker operating mechanism mounted on said circuit breaker, a connecting bar from said operating mechanism to said trip mechanism, said bar being mounted on said racking :ebanvsaid operating mechanism whenisaidfcircuit msbreakerl is moved relativectowsaid cubicle opcrating through :said connectingcbarato operate a said trip mechanism to tripvsa-id circuit breaker.

6. A circuit breaker constructed for. movement tinto and out of a cubicle an'dhavin'g primary distconnect contacts; said circuitbreakerkhdving a. circuit closed and a trip :openuposition, a trip "mechanism for. operating isaicl; circuit 'breaker to tits trip, open position, a screw carried bywsaid .z'circuit breaker;v a smoking bancarried by- -=said 11:.SC1'6W, a locking'member' forssecuring said-rackwing bar to said cubicleto permit movement of wsaid. screw and circuit :floreaker rrelative-i to said racking bar and. cubicle foriraicking saidcircuit- .=.tbre.aker into racked-inand -racked-outpositions, atcircuitbreaker operating mechanism mounted JOniiSald circuit breaker; a connectingbar from 11said"operatingtmechanism torsaic'- trip mecha- J nism,':said bar being mounted on said racking bar, said'operating mechanism: when" said circuit "breaker is moved relative to said cubicle'operat ingcthrough saidflconnecting bar to'operate said it'trip mechanism to trip said circuitibreaken' and an adjusting mechanism on said rackin'g'bar for zit adjusting the connection of said conneotin bar "vrelative to said circuitbreaker operating mecha- .nism.

A..circuit breaker-having a trip mechanisin constructed for movement into and out of a cubi--- 1 cle; a cam mounted on said circuit breaker; a scam' follower engaging said cam, a racking-bar, a 'cam follower'bar'providing a connection from said cam. follower to'said racking bar, said cam ."having a surface'at one end'thereof engageableuby said follower when said circuit breakeris in 1 its racked-in position and having a surface" en- -gageab1e by said follower at its other end-when said circuit breaker is in its racked-out position and having a surface intermediate said position engageable by said follower so that said cam I follower is instantly operated by said cam when therracking-out of said circuit breakerstarts for operating-said circuit breaker to its trip open position and for positively maintaining saidcircui't breaker in its trip open position'untiltsaid "1 circuit breaker has been moved to' its -rackedout :position.

8 r: 8: A: circuit :brakerhaving a' trip -mechanism and disconnectcontactsi constructed for movement into and out of a cubicle; a camumounted on saidcircuitrbreaker; ai racking :bar; a cam follower bar-providing a connection from 'said v:cam followerrtosaidrackingibar;saidcamdiaving afsurface at i one end thereof. engageable byi said .c-fol'lower when said circuit breaker isw-in its aracked-in positionl and having a surfaceengageable-byrsaid' follower at its? other. end when said.

;.,.,circuit' breaker. is in its :rackedout :position and .lwhavi'ng aisurfacezintermediate' said rposition engageabie by'said; followenso': that: said cam-fol- 1 lower is; instantly operated bywsaidicam 'whenz-the racking out of said: circuit breaker starts for :woperating said circuit breaker to its trip 'open position" before said disconnects disengage "and 1 for positively. maintaininglsaid :circuit brea-kento Jits tripsopeneposition untilsaid' circuit breaker hats been movedsto its racked-out position; and an adjustin wmechanism mounted on said circuit 1 breaker for adjusting said connection to properly po'sition said can'i follower on said cam.

9. A circuit breaker constructed for movement into and outof a cubicle and-having primary disconnectcontacts-said circuitbreaker havinga "circuit closed and a; trip open position, a trip mechanism for operating-said circuit breaker to -its trip open position, a circuit breaker operating -mechanism mountedon'said: circuit breaker; a

"connecting :bar fromsaid'operating mechanism to said trip mechanism, said operating mechanism when said circuit breaker ismoved relative to said cubicle operating through'saidconll'c Cting bar" to operate' saidtrip inechanisn'i to :tripsaid circuit breaker, and "an "adjusting urnechanism for adjusting the connection of a cam follower barrelative to said-circuit breaker operating mechanism, said cam followehbar being stationarvwith respectto said cubicle during the racking-in oroutmovements of said circuit breaker.

References Cited =m the 1 file of this patent 

